I too have pain under my right rib cage that radiates around my rib cage and through to my back behind my right rib cage. Most interesting is I sometimes feel as though there is a small air pocket under my ribs (I even told the doctor this).
I'm a 37 yo 215 lb male with elevated cholesterol and have had this for several years. Its seems to be getting worse. I've had several ultrasounds and a CT scan. No stones have been found.
I've been a marijuana smoker on and off for 25 years. I've found it hurts more when I smoke. Pot smoking leads to an unhealthy diet, so it could be that or possibly the dehydration. If I drink a ton of water and don't smoke, it gets a little better. I'm a programmer and spend the majority of the day behind a computer holding the mouse in my right handed, so there may be a link there. Sometimes exercise and stretching seems to help. However, nothing has every made the pain truly go away for more than a week.
I also have gerd and an endoscopy a couple years ago found lesions in my esophagus.